This invention relates generally to an assembly that connects an adapter and needle to a tube for fluids such as a catheter or feed line for chemicals and the like.
In medical applications, it is often necessary to disconnect a drug delivery system connected to a catheter, for example, for the purpose of changing reservoirs or moving the patient. As a result, contaminants from the air or the surroundings may enter the open end of the tube that has been disconnected, adversely affecting the sterility of the line.
Related thereto, outpatient treatment for various illnesses frequently necessitates repeated injections of drugs by the patient at home. As a result, it is necessary to continuously remove and reinsert a catheter in the patient's body. Accordingly, hard teflon catheters have generally been used for such purpose. It would, however, be more desirable to utilize a soft catheter made of, for example, polyurethane, which could stay in the patient's body for an extended period of time on the order of a plurality of weeks or a month. Such soft catheters could be made much smaller, for example, having an outer diameter of 0.014 inch and an inner diameter of 0.004 inch, and would be more comfortable to the patient. However, in order to maintain such a catheter in the body for a long period of time during numerous reservoir changes, the internal catheter lumen must remain sterile in order to prevent contamination at the injection site.
In this regard, U.S. Pat. No. 4,659,043 discloses an assembly including a locking septum fitting which permits the disconnection and reconnection of a drug delivery system to an inserted catheter line while still maintaining sterility and leakproof characteristics within the catheter. In this regard, an assembly is disclosed therein which includes a septum disc that is compressed between a distal end cap and proximal connector connected to the distal end cap, so as to provide a self sealing, sterile, static barrier to a fluid being fed from a septum piercing tube, such as a needle, in an external adapter fitting connected to the proximal connector. However, the assembly of this Patent uses a seal that depends upon compression by the mating distal end cap and proximal connector. As a result, sealing occurs at the opposite faces of the septum disc which are contacted by respective portions of the distal end cap and proximal connector. In other words, the seal is not very efficient and because of the compression that is used to provide such seal, the seal may fail over a period of time, which could be disastrous to the patient. Also, because of such sealing arrangement, the component tolerances of the distal end cap and the proximal connector must be maintained very closely to insure proper sealing, thus greatly increasing the cost. Also, this arrangement limits the types of material that can be used for the septum itself. Specifically, some portion of the material must be sufficiently rigid to provide the proper support, while also allowing for repeated puncture.
However, the proximal connector and the distal end cap in this Patent are bonded together in order for the device to be operative. Thus, the proximal connector and the distal end cap must be held together in compression during the bonding operation. The bonded seam must also provide a static seal, as well as maintaining compression on the septum.
This Patent also discloses a taper sealing with a threaded lock connection between the external adapter fitting and the proximal connector.
An extension set and injection site is also sold by ICU Medical, Inc., 5200 Warner Avenue, Suite 108, Huntington Beach, Calif. 92649. With such device, the extension set includes a septum cap covering the end of an end cap. Such septum cap, however, is exposed at one end thereof, and as such has no secondary seal when connected to the external adapter fitting. In addition, an external adapter fitting which includes the needle extends over the septum cap during piercing thereof by the needle. However, an external snap-securing device is provided on the external adapter for securing the same to the extension set. This device complicates the assembly and makes it difficult to work with. This snap-securing device does not in itself provide a seal. The seal only takes place through the septum.
In the ICU device, there is a cowling that extends over the needle to provide a stickless needle.